- This is a backtracking problem
- To avoid duplicates but also preserve the order of original elements, you cannot just used
usedto check duplicates on the
same tree levelbefore adding them to your path.
- Need to add
every qualified nodeinstead of just
Given an integer array nums, return all the different possible increasing subsequences of the given array with at least two elements. You may return the answer in any order.
The given array may contain duplicates, and two equal integers should also be considered a special case of increasing sequence.
Input: nums = [4,7,6,7]